1. Field of the Invention
This invention relates to a camera unit and a camera system using the unit.
2. Description of the Related Art
Recently, there are proposed, as the camera unit, various camera units including an on-vehicle camera unit for supporting driving of a vehicle, a surveillance camera unit for preventing crimes and disasters, a terminal-oriented camera unit for portable electric information terminals and the like. As such a camera unit, there are known, for example, one in which a substrate having an imaging device is provided with an imaging element drive unit, an image processing unit, a CPU and peripheral circuits such as a memory and the like (see JP 2008-54097 A, for example), and one in which a substrate having an imaging device is provided with a lens unit (see JP 2008-306350 A, for example), in order to achieve downsizing.
There is also known a camera unit in which, in order to take an image covering a wide field of view, a prism is disposed in the front side of an imaging lens, and light from a plurality of field of views incident on the prism is divided and imaged on a single imaging device through an imaging lens, thus taking images of a plurality of field of views all together (see JP 2000-89301 A, for example).
However, when using a normal lens with a field angle of about 120° or a fish-eye lens with a field angle of about 200°, for example, in the camera unit disclosed in JP 2008-54097 A or JP 2008-306350 A, the peripheral portion of an image formed on an image element is distorted and the visibility is thus deteriorated. Moreover, the improvement of the visibility requires image processing software for performing interpolation processing, distortion correction processing or the like on the peripheral portion of image data obtained by the imaging device, which increases the cost and deteriorates the usability for users.
In the camera unit disclosed in JP 2000-89301 A, moreover, a prism is disposed in the front side of an imaging lens, so that a length projecting forward from a light receiving surface of the imaging device becomes longer, and the camera unit becomes thicker.
Therefore, an object of the invention made in view of the above aspects is to provide a camera unit which is easily applicable for taking images covering a wide field of view and capable of taking images having good visibility and, further, which enables thinner profile and cost reduction, thus improving the usability for users, and a camera system using the unit.